Feeding mechanism for offset printing machines



Nov. 29, 1938. P. H. DURUP FEEDING MECHANISM FOR OFFSET PRINTING MACHINES Filed Oct. 14, 1937 INVENTOR PM Z4 7 ATTORNEY Patented Nov. 29, 1938 UNITED vsinres PATENT OFFICE FEEDING MECHANISM FOR OFFSET PRINT- lNG MACHINES Paul H. Dump. Wollaston, Mass., assignor to Art-O-Graphic Printing Company, Inc.. Boston, Mass., a corporation of Massachusetts Application October 14, 1937, Serial No. 168,853

7 BjCiaims. (Cl. 271. 12)

means have been perfected, referred to in my co-pendlng application Ser. No. 122,543, filed January 27, 1937, making possible the printing of envelopes in themanner referred to at greatly increased rates of speed, as many as 5,000 envelopes per hour and more being printed. As a result very eiiicient and accurate feeding mechanism is required and with such production rates the nature of envelopes in and of themselves give rise to specific feeding problems. The quality and thickness of paper is a factor, the occurrence of warped edges must be taken care of, and there are peculiar difliculties arising from sagging of stacks of envelopes when in position to be fed into a printing machine. The present mechanism overcomes such difliculties and makes possible the feeding of 5,000 or more envelopes per hour.

The principal object ofmy invention therefore is an improved feeding mechanism.

Another object is means for holding and feeding envelopes.

Another object is means for overcoming feeding difficulties occurring from non-uniformly shaped envelopes.

Other objects andnovel features comprising the construction and operation of my invention appear in the following description.

In the drawing illustrating the invention:

Fig. 1 is a view in side elevation fragmentarily indicating a printing machine and the improved feeding mechanism associated therewith.

Fig. 2 is an end elevation looking in the direction indicated by line 2--2 of Fig. 1.

Fig. 3 is a detail plan view of an envelope stack holder. V

Fig. 4 is an enlarged cross section taken on the line 4-4 of Fig. 2.

Referring more in detail to the drawing, ill ini5 comprise driving means for the printing mechanism above referred to.

Mounted between the sides I2 is a shaft l'l which is rotated by a gear mechanism forming a part of the printing machine proper and not shown in the drawing. Mounted on shaft I1 is sprocket I8 carrying a chain l9 which drives sprocket 20- mounted on a shaft 2| pivotally secured between sides I 2 at the outer end of the feeding mechanism.

Fixed on shaft 2! are pulleys 22 which drive conveyor belts 23 also passing over a pulley member located on shaft l1. It may also be desired to provide another belt occurring midway between the belts 23 and driven in a similar manner to those already described.

blocks 21 provided with adjustment screws 28 and carrying angle members 29 projecting upwardly,

to form corners of a frame for receiving envelopes. Adjacent the blocks 21 are additional block members 30 similarly adjustable by screws 3i and formed on their inner sides with shelf portions 32.

The remainder of the frame is made up of a pair of straps 33 fixed to the angle members 29 and across the edge is adjustably porting pieces 33 inset to leave edges 39 for receiving the edges of envelopes.

It will be noted that a very efllcient rack is effected by this construction in which a stack of envelopes 40 is supported along front and rear edges and the whole structure can be adjusted in two dimensions to adapt itself to various sizes of envelopes. In handling such subject matter, it has been found that stacks of envelopes, owing to certain warped conditions or other reasons, may tend to lie unevenly and may sag at the middle. By providing two support members 38 at one edge, and the adjustable edges 32 at the other edge, it is possible to maintain the stack in correct position for removal of single units and a substantially straight alinement of the bottom envelope in the stack is effected since the edges 33 are substantially in the same plane. The significance of maintaining correct position of the envelope stack will be again referred to in connection with means for removing single envelopes therefrom.

Mounted above shaft 2| is a second shaft 4i being received at its ends in bearings 42. Fixed at one end of shaft 4| is a rod and link mechanism l3 and 44 and spring a, in which the rod member extends forwardly to the frame of the printing machine proper to connect with a cam follower unit 45 received on the inner side of a lever member 48. The cam follower unit is adapted to contact a cam 41 which is. actuated by the driving mechanism of the printing machine, and the movement of the cam in this particular instance will be such that for eachcomplete rotation of the printing rolls with the cam, the link will pass through one complete cycle.

Solidly fixed on shaft II are a pair of curved arms 43 having secured at their extremities suction cup members 49. Attached to the suction cups 49 are air conduits 50 which connect with a switch 5| controlling passage of air through conductor 52, which in turn is connected. to some mechanical suction means of a conventionalorder not shown in the drawing. The switch ii is provided with some desirable valve means for opening and closing the air passage to the suction cup at predetermined intervals during the cycle of movement of the suction members. The operation of the suction members as actuated by the rod 44 is to pass forward and upwardly into engagement with the bottom envelope of a stack such as 40 illustrated in Fig. 2. As the suction cups pass into contact with the envelopes, suction is occurring and the envelope will be removed from the stack by the edges 32 and 39 and passed downward upon the belts 23 slightly before which time the suction has been shut off, so that the envelope is free to move along on the belt.

It is understood that suction means for removing stacked subject matter to be printed is known in the art. However, in the present mechanism as many as 5,000 or more envelopes per hour are being fed into the machine and dimculties arise. For instance, at such a rate of speed, there may occur contacting of the suction cups in its upward path with an envelope that it has just deposited on the belts if for any reason the envelope has been slightly delayed in its passage' along the belts. This difilculty is thought to be peculiar to the treatment of envelopes. To overcome this, the shape of the cam 4'! is such that a portion of its surface, roughly speaking a third, is a true circle whereby the curved arms when this part of the cam is driving will be held at rest by spring 44-11, and the practical result of such a mechanism under high-speed conditions is to effect a very slight dwell in the movement of the curved arms 48 which allows the envelope which has just been dropped on the belts to move ahead out of the way of the suction cups coming up for the next operation.

In Fig. 4 I have shown roll members 53 which will preferably be composed of some soft resilient material such as sponge rubber. These rolls are provided to insure advancement of an envelope on the belts 23 as fast as possible.

It has been found that by locating the periphery of these rolls directly under the point at which the front edge of an envelope occurs, best results may be obtained. Several difficulties CHIS.

arise in the handling of an envelope at this particular point. There may be the possibility of an envelope having its front edge projecting up from the belts sufficiently to impede its passage just long enough for the suction cups to come up and break the sequence of operation. By positioning the roll periphery in the manner referred to, there is a tendency for the clockwise rotation of the roll to absolutely prevent uplifting of the front edge of the envelope. Another difliculty which occurs at this particular point results from different thicknesses'of paper of which the envelope may be composed. Such variance in thickness may result in failure of the envelope to be carried between the belt and the roll fast enough. To further overcome such a condition the roll 53 has been provided-with an elongated slot 54 so that the roll mounted 'cn shaft 55 is in a substantially floating position relative to its contact with the belt 23 and thereby adapts itself to a variance in the thickness of the envelope passing between it and the belts. It may further be desired to use additional belts farther along to further insure steady progression of envelopes to the printing means.

One of the more important results achieved by the frame structure shown is maintenance of the envelopes in a substantially flat state by the application of the supporting edges in the particular manner shown, while providing an opening for the suction members to come up from beneath the pile in contrast with the conventional method of working from the top of the pile.

Very slight change in the position of the bottom envelope in the stack may result in failure of one of the suction members to properly engage the envelope and in such case, only one end of the envelope is carried to the belts and clogging oc- In addition to avoiding such complications, the frame is of such adjustable nature as to adapt itself to a great variety of sizes such as is constantly being encountered in filling orders from diflerent companies.

The action of the suction members together with the rolls 53 and the frame pieces 33 and 34 and the edges 32 combine to effect a steady accurate removal of envelopes from the bottom of the stack, which is adaptable to various non-uniformities particularly occurring with envelopes. The exact means of overcoming the difficulties referred to may be varied to some extent in size or shape of structure while still effecting the functions set out above.

Having thus described my invention, what I claim is:

1. In an offset printing machine a feeding mechanism for feeding envelopes, comprising in combination a frame, an endless carrier in. said frame, holding means located on said frame, said holding means provided with adjustable shelf portions for holding two sides of an envelope stack, suction means pivotally mounted in said frame adapted to engage with the bottom unit in the said stack by uniformly pulling an envelope away from the said edges uniformly and releasing it upon the carrier member, roll means located in said frame in floating engagement with said carrier for advancing envelopes therealong, and being located in such manner that their peripheries fall directly and tangentially under the forward edges of envelopes in the said stack.

2. In a printing-machine a feeding mechanism for feeding envelopes, comprising in combination a frame, endless carrier means located in said frame, holding means located on said frame above the endless carrier for holding envelopes in stacked relationship, means for removing envelopes singly from the bottom of said stack and depositing them in a substantially horizontal position .on the said endless carrier, driven roller means being so located as to prevent upturning of the front edge of an envelope which has been located on the endless carrier, and means for maintaining said roller means in floating engagement with the endless carrier whereby constant engagement of subject matter is effected between the carrier and the roller means irrespective of the thickness of the envelopes.

3. In a printing machine, a feeding mechanism for feeding envelopes comprising in combination a frame, an endless carrier in said frame, and a holding means for holding envelopes in stacked relationship,-means for withdrawing an envelope from the bottom of the holder and releasing it in a substantially alined position on the carrier, being cooperatively associated with driven roll means so located as to engage the envelope immediately after it has been located on the carrier, and said driven roll means supported in slotted bearings whereby self-adjusting engagement of the driven rollwith the endless carrier is effected.

4. In a printing machine, a feeding mechanism for feeding envelopes comprising in combination a frame, an endless carrier and a stack holder, said stack holder comprisinga plate, upright members adjustably located on said plate, adjustable supporting edges on said plate between said upright members, rearwardly extending straps comprising the sides of 'said holder, being slotted at their extremities to receive a trans.-

verse strap similarly slotted at its ends whereby two-way adjustment of the holder dimension may be effected, and an adjustable shelf and upright member movably located on said transverse strap.

5. In a printing machine a feeding mechanism for feeding envelopes comprising in combination a frame, an endless carrier in said frame, and a stack holder mounted directly over said carrier for receiving a stack of envelopes, said stack holder comprising front and rear supporting edges and front and rear upright portions, said supporting edges being adjustable relative to their location to one another, said rear upright members being adapted to-engage a stack of envelopes therein, means for removing envelopes occuring horizontally therein from the bottom of said stack, and means for engaging an envelope as it-is lowered and after it .en-

gages with the endless carrier to insure its pasdirectly andtangentially under the forward edges of the units in said stack.

[7. In a mechanism for feeding envelopes, sheets and like materials, in combination, a frame, carrier means, supporting means for a stack of said material, suction means adapted to engage the bottom unit in the said stack and to pull said unit away from the stack and release it upon the carrier member, roll means for advancing units'along the carrier, said roll means being so located as to present a peripheral surface falling directly and tangentially under the forward edges of the units in said stack, and means for delaying the return movement of the suction means toward the stack for that period of time required for a unit of subject matter to pass into engagement with said roll means after it has been desposited on said conveyor.

-8. In a mechanism for feeding envelopes, sheets and like materials, in combination, a frame, carrier means, supporting means for a stack of said material, suction means adapted to engage with the bottom unit in the said, stack and to pull said unit away from the stack and release it.

upon the carrier member, roll means so located in the frame that the front edge of a sheet when removed will fall directly under the roll periphery, and means for delaying return movement of the suction members toward the stack until a sheet passesalong the conveyor to the position in which it is engaged by the said roll.

PAUL H. DURUP. 

